1. Field of the Invention
The present invention is directed to the mechanical locating of circuit substrates during the manufacturing process; and more particularly to a work or printer table arrangement for use in locating alumina substrates for laser scribing during thick film circuit pattern printing.
2. Background Art
In previous arrangements, substrates were typically pushed manually against the locating pins of the printer table and then fixed in position by a vacuum actuated by an operator's footswitch. This particular method was slow and inconsistent in alignment as well as inconsistent in loading force often resulting in damage to the substrates.
Upon automation of the thick film printers, the substrates were positioned by a mechanical locating mechanism. The mechanism in one particular example consisted of six spring-loaded linkages driven by a linear cam with a vacuum, actuated by a limit switch fixing the substrate position after locating was complete.
In this particular system, four major problems developed. The first of these was positioning and timing of the linkages which was difficult and time consuming; second, the linkages would often wear out over time requiring replacement; third, the linkages had to be adjusted each time the substrate thickness or pattern orientation was changed; and fourth, the system could only handle rectangular substrates within a plus or minus one percent size specification.
Another variation of this system utilized air cylinders and limit switches to actuate the linkages instead of springs and cams. The system decreased the number of required linkages but was rough on the substrates, often causing damage. Also, as with the previously outlined system, it required adjustment depending on the substrate thicknesses and pattern orientation and could not be used for oddly-sized or shaped parts.
In addition, due to the space requirements of both these systems, they were only applicable to the printing machinery and could not be utilized in laser scribing and laser trimming operations. These functions remained manual operations.